What happened to metro New Orleans in 2005 was unprecedented in the history of the United States. It included the vast displacement of hundreds of thousands of people after Hurricane Katrina. But since then, the city at the epicenter of the storms and levee failures has been coming back in terms of population and economics.

Until now.

In new U.S. Census Bureau figures, New Orleans saw its population shrink by nearly 1,000 between 2016 and 2018. Needless to say, as people have been returning — and new residents have joined in a growing business and jobs recovery — it’s a milestone.

The Census figure of just over 391,000 residents is about 80 percent of its pre-Katrina population in 2005.

But New Orleans, as iconic as the city is in so many ways, is also part of the whole of Louisiana, where population declined by about 10,000 — a fraction of a percentage point, but still troubling.

And as in New Orleans proper, the decrease was a function of more people leaving than people moving in or being born.

About 27,000 more people chose to move out of the state than into it, a number that was somewhat offset by the fact that more people were born than died.

''In Louisiana, we have a fundamental problem attracting the businesses and the industries that are attractive to populations that are more likely to migrate,'' said Robert Eisenstadt, an economics professor at the University of Louisiana at Monroe.

''When you look at 27,000 people leaving the state, that's got to be a work-related consequence,'' he said.

Probably, and what can be done about that?

Hurricanes Katrina and Rita in the same year were dramatic alterations in the direction of Louisiana and have had far-reaching impacts. Growing population, once the surge of returning families slows, is by its nature a step-by-step process.

In Louisiana, where an oil-and-gas bust at the end of 2014 causes significant job losses in southern Louisiana, recovery has been slow but includes upticks in personal income and other vital indicators. For New Orleans in particular, suburban parishes in the region continued to grow, and nationally many such center-cities have lost a bit of population recently — perhaps a function of housing costs, which have steadily risen in the Crescent City as elsewhere. Lafayette Parish has grown every year since 1989, even with the latest oil price slump, and Baton Rouge's metro area still shows some of the impact of the disastrous 2016 flooding.

But for both New Orleans and Louisiana, a renewed commitment to economic diversification and educational attainment is the key to prosperity that outlasts oil price collapses, or even damaging storms and floods.

New hires flow into the DXC Technologies building on Poydras Street, and that building is not alone, either in the city or in Louisiana, particularly in Baton Rouge and Lafayette. These should be beacons of what we still need to do in making our state more vibrant economically, and not dependent on any one industry.